1. Field of the Invention
The present invention is directed to a catheter, for example a retrieval or delivery catheter used in medical applications, which has an expandable end portion.
2. Discussion of the Background
Catheters are well known medical devices used to facilitate various medical procedures, such as diagnostic or delivery procedures. Catheter tubes are inserted into a body of a patient for various medical procedures. For example, a catheter may be used in performing diagnostic procedures such as removing a sample from a body site of a patient. The catheter tube is used in this situation as the delivery vehicle for the medical instrument which removes the sample. Further, sophisticated medical implant devices, such as filters and stents, can be delivered and retrieved into and from the body site of the patient using a catheter.
Generally, a catheter has a tube portion which is relatively stiff in both axial and radial directions to allow proper placement of the catheter in the patient's body, but which may be fitted with a distal soft tip which first contacts tissues in the patient. The soft tip is provided to minimise discomfort for the patient when the catheter is inserted into the patient. For example, WO-A-9808562 A describes a catheter with an insert moulded catheter tip. However, there are constraints on the use of such catheters in that such catheters can only be relatively small sized, and thus can only be used to retrieve and deliver relatively small samples and medical devices.